As spacecraft become larger, the heat they produce also increases. That means vehicles built for long-term space exploration need more efficient cooling systems. The Two-Phase Flow investigation looks at the heat transfer characteristics of how boiling liquids turn into vapor in microgravity. Flow boiling is boiling with forced flow over a heated surface, while two-phase flow refers to both phases – vapor and liquid – flowing together in a single channel or tube. Using a loop with a transparent heating tube aboard the International Space Station, researchers will establish flow rate, heating power, ratio of vapor to total flow, and other effects under different conditions. These data will contribute to better fundamental understanding of the behavior of liquid and vapor and the mechanism of how heat is transferred in microgravity. On Earth, this understanding has potential applications in cooling system design for high performance computers, data servers, and electric vehicles. Credi...